1. Field of the Invention
The present invention relates to an objective, a microscope using the same, an optical analyzer, and a method of driving the analyzer.
2. Description of the Related Art
Generally, in a microscope with upright frame, focusing is carried out onto a sample such that a distance between the sample and an objective is made to be an operating distance. At this time, when a lens surface or a lens frame of the objective contacts the sample or a cover glass, the objective or a specimen may be damaged. For this reason, an attempt is made to leave a sufficient distance between the objective and the specimen in advance in order to prevent the objective or the specimen from being damaged.
On the other hand, the same holds for an inverted microscope in which an objective is arranged under a specimen plate or a micro plate, the inverted microscope being used for an optical analyzer, and an attempt is made to leave a sufficient distance between the objective and the plate in order to prevent the objective from contacting the bottom face of the plate.
However, the surface of a sample may be highly convex or concave, or a cover glass and a plate may be inclined. In such a case, when the sample, the cover glass, and the plate are shifted in a plane perpendicular to an optical axis of the objective in order to change an observing position in a case where the objective is very close to the sample, the cover glass or the plate, the objective, the lens surface or the lens frame of the objective may collide with the sample, the cover glass, or the plate, and the sample, the cover glass, and the plate are in some cases damaged.
In particular, in a case of a micro plate for use in an optical analyzer, it is difficult to measure respective wells continuously when there is a strain in the entire micro plate, or the thickness of the bottom is uneven, or the bottom face of the micro plate is strained due to undulation being brought about in the bottom plate even if the thickness of the bottom is even. Consequently, the operation efficiency for optical analysis is greatly deteriorated.
As a countermeasure, a confocal scanning optical microscope as will be described below is disclosed as a method of preventing damage to a sample or an objective due to the lens surface or the lens frame of the objective contacting the sample, (refer to Jpn. Pat. Appln. KOKAI Publication No. 8-190053). To determine an observation range or a measurement range of a sample, a shift only to a direction along which the objective and the sample become closer is first permitted. Next, when a focal position of the objective is shifted onto the uppermost surface of the sample, this is an upper limit. Then, a control is made such that, by sequentially permitting a shift to a direction along which the focal position of the objective and the sample are contacted with or are apart from, a position where the focal position is set to the lowermost surface on the top surface of the sample can be found. When a shift amount of the objective exceeds that an operating distance, the shift is stopped.
Further, in order to protect a sample, a microscope system is disclosed in which a tactile sensor for sensing contact with a sample is provided to an objective, and a stage is shifted in a direction that the sample is kept away from the objective by a sensor signal from the tactile sensor (refer to Jpn. Pat. Appln. KOKAI Publication No. 2000-199858). Moreover, an objective for a microscope is also disclosed in which an internal cylinder for holding an apical lens of an objective is biased upward by a coil spring, and when an apex of the objective bumps into, for example, a container, a buffering action of the coil spring acts, which prevents the apical lens from being broken (refer to Jpn. Pat. Appln. KOKAI Publication No. 10-123426).